The present invention relates to position detecting circuit for detecting relative position between objects, and relates to apparatus using the position detecting circuit.
Because of their relatively low cost, sensor systems using a permanent magnet and Hall effect device (magnetic field detecting device) are widely used as the system for detecting relative position between objects. In such a case, since Hall effect device possesses a temperature characteristic, there is a problem that sensitivity of the Hall effect device is changed and its position detecting accuracy is lowered with change in the ambient temperature. To solve this problem, Japanese Patent Application Laid-Open hei-7-181557 discloses a temperature correction means composed of a transistor having a temperature characteristic of an opposite polarity from the temperature characteristic of the Hall effect device, and a voltage dividing resistor and regulating resistor so that an electric current through a drive power supply of the Hall effect device is changed in accordance with the temperature change.